Envisioning the unseen universe : models of the ether in the nineteenth century

Author:

Haley, C. D.

Awarding Body:

University of Cambridge

Current Institution:

University of Cambridge

Date of Award:

2002

Availability of Full Text:

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Abstract:

This work centres upon nineteenth century treatment of the luminiferous ether (æther), the hypothetical medium for the transmission of light and other phenomena. In particular it concerns the philosophical problems raised by the apparently contradictory properties of this substance; the methodological problems of dealing with a substance which was both invisible and insubstantial; and the models which were designed to represent this medium. Although it refers to aspects of ether physics throughout the nineteenth century, the primary focus of the work is the period 1850 till 1890. The thesis examines several of the more significant ether models, asking what exactly was their role, how important they were in the process of theory-formation, how realistically they were viewed, and other questions. It also seeks to identify other factors besides the failure of experiment which were influential in leading physicists towards mechanical modelling. To this end, it discusses cultural factors including Victorian attitudes towards construction and machinery, the academic context in which most of the ether physicists were working, and a series of other influences (including spiritualism and the new Energy physics) which were conducive to a highly realistic view of the ether and to the construction of mechanical representations. It also examines the natural philosophy which was required to license the use of models as tools of research, and demonstrates that there was a high degree of conscious debate among physicists about the philosophical problems of modelling. Finally, the work seeks to explain why the mechanical ether models were eventually discarded at the end of the nineteenth century. In doing so, it suggests that the transition from ether to electromagnetic field should be best considered as a shift from what may be termed entity realism to structural realism, and makes some observations about the role of scientific models in general.